Institute of Rheumatology, Prague, Czech Republic, Na Slupi 4, 120 50, Prague 2, Czech Republic.
Department of Rheumatology, First Faculty of Medicine, Charles University in Prague, Czech Republic, Na Slupi 4, 120 50, Prague 2, Czech Republic.
Clin Rheumatol. 2018 Aug;37(8):2055-2062. doi: 10.1007/s10067-018-4091-5. Epub 2018 Apr 14.
Approximately half of patients with rheumatoid arthritis (RA) have normal C-reactive protein (CRP) levels. Calprotectin is a promising and likely more specific biomarker of disease activity than conventionally used acute phase reactants. We aimed to analyse the levels of serum calprotectin in RA patients with clinically active disease and with normal/low CRP. A total of 160 RA patients underwent clinical examination (DAS28-ESR and CDAI). The levels of calprotectin were analysed in patients with moderate to high disease activity with normal/low CRP levels and in 32 healthy subjects. The discriminatory capacity of calprotectin to identify clinically active patients in spite of normal/low CRP was assessed using ROC curves. Out of all RA patients, 74/160 (46.3%) were in remission or had low disease activity according to DAS28 and had normal/low CRP levels. However, 51/160 (32%) had normal/low CRP levels despite having moderate to high disease activity. In these patients, calprotectin levels were significantly higher than those in patients who had normal/low CRP and were in remission or showed low disease activity (2.7 ± 1.5 vs. 2.1 ± 1.2 μg/mL, p = 0.043), which differed from those in healthy subjects (2.7 ± 1.5 vs. 1.9 ± 1.2 μg/mL, p = 0.011). The discriminatory capacity for calprotectin to distinguish clinically active vs. inactive disease despite normal/low CRP using AUC of the DAS28 was 0.607 (95% CI 0.503 to 0.711, p = 0.043). The present study demonstrates that calprotectin may reflect inflammatory activity in RA patients where CRP fails to do so.
约一半的类风湿关节炎 (RA) 患者的 C 反应蛋白 (CRP) 水平正常。钙卫蛋白是一种很有前途的生物标志物，比传统的急性期反应物更具特异性，可用于评估疾病活动度。本研究旨在分析临床活动期且 CRP 正常/低值的 RA 患者的血清钙卫蛋白水平。共 160 例 RA 患者接受临床检查（DAS28-ESR 和 CDAI）。分析了中高度疾病活动且 CRP 正常/低值患者以及 32 例健康对照者的钙卫蛋白水平。采用 ROC 曲线评估钙卫蛋白在 CRP 正常/低值的情况下识别临床活动期患者的能力。在所有 RA 患者中，根据 DAS28，74/160（46.3%）例患者处于缓解期或疾病活动度低，且 CRP 水平正常/低值。然而，51/160（32%）例患者尽管疾病活动度为中高度，但 CRP 水平正常/低值。这些患者的钙卫蛋白水平明显高于 CRP 正常/低值且处于缓解期或疾病活动度低的患者（2.7±1.5 vs. 2.1±1.2μg/mL，p=0.043），且高于健康对照组（2.7±1.5 vs. 1.9±1.2μg/mL，p=0.011）。使用 DAS28 的 AUC，钙卫蛋白区分 CRP 正常/低值时临床活动期与非活动期疾病的诊断能力为 0.607（95%CI 0.503-0.711，p=0.043）。本研究表明，钙卫蛋白可反映 CRP 未能反映的 RA 患者的炎症活动。
